1. Field of the Invention
The present invention relates to downhole packers. More particularly, the present invention relates to packers adapted to seal an annular space within a wellbore. The packers, for example, may be utilized to circulate or reverse circulate a fluid.
2. Background of the Related Art
In certain downhole applications utilizing a fluid (i.e. fluid, viscous fluid, cementation slurries, sand slurries, and acids), there is fluid remaining in the tubing string when the application is completed. Since the tubing string may be thousands of feet long, it is undesirable to pull the tubing string out of the hole with the fluids remaining in the tubing string. When pulling a xe2x80x9cwetxe2x80x9d tubing string, the contents of the tubing string are unmanageably dumped and released at the top of the oil platform when disconnecting the tubing. It is also undesirable to open a valve at the bottom of the tubing string to release the fluid contained in the tubing string down into the wellbore. The fluid may comprise a cement slurry which if released down into the wellbore will eventually harden and solidify. Therefore, there is a need for an improved tool adapted to circulate or reverse circulate a fluid out of the tubing while not allowing the fluid to fall to the bottom of the wellbore.
Current packers are unsatisfactory to circulate or reverse circulate fluid out of the casing. Packers are typically used to seal an annular space formed between two tubular surfaces. A packer may seal, for example, an annular space formed between production tubing disposed within wellbore casing. Alternatively, a packer may seal an annular space between the outside of a tubular and an unlined wellbore. Common uses of packers include protection of casing from pressure (including both well and stimulation pressures) and corrosive fluids; isolation of casing leaks, squeezed perforations, or multiple producing intervals; and holding of treating fluids or kill fluids.
Packers typically are either permanently set or retrievable from a wellbore. Permanent set packers are installed in the wellbore with mechanical compression setting tools, fluid pressure devices, inflatable charges, or with cement or other materials pumped into an inflatable seal element. Retrievable packers have a means for setting and then deactivating a sealing element, thereby permitting the device to be pulled back out of the wellbore.
Typical retrievable packers are weight-set packers which require the rotation of the tubing and movement of the tubing up and down to activate a xe2x80x9cJxe2x80x9d slot device. One problem with utilizing current weight-set packers is that it is difficult to rotate long lengths of tubing. Another problem is utilizing a weight-set packer in conjunction with coil tubing. Coiled tubing is a continuous flexible string of metal tubing which is brought to the well site on a large reel. One advantage of using coiled tubing is that the tubing is easily run and pulled from a wellbore. Furthermore, coiled tubing may be able to traverse non-linear paths. However, because of the flexibility of the coiled tubing, it is difficult to rotate the tubing to activate a weight-set packer.
Therefore, there is a need for an improved packer which does not utilize rotation to set the packer.
The present invention relates to packers adapted to seal an annular space within a wellbore. The packers, for example, may be utilized to circulate or reverse circulate a fluid. In one embodiment, the present apparatus comprises a first tubular subunit and a second tubular subunit moveably coupled together, a flexible packing element disposed between the first tubular subunit and the second tubular subunit, and a temporary mechanical connection adapted to restrain the first tubular subunit and the second tubular subunit from compressing the flexible packing element, in which the temporary mechanical connection is adapted to be hydraulically disengaged. In another embodiment, the present apparatus further comprises a valve. In one aspect, the present apparatus further comprises a cement inflation tool. In still another embodiment, the present method comprises locating an apparatus, comprising a packer and a valve positioned above the packer, at a predetermined location within the wellbore; setting the packer, the method of setting the packer comprising, applying a first hydraulic pressure within a central bore of the apparatus and applying down weight on the apparatus; and opening the valve. In one embodiment, the present method comprises actuating a displacement device to displace a fluid below a packer; setting the packer by utilizing a predetermined fluid pressure to disengage a temporary mechanical connection between a first surface and a second surface of the packer and by compressing a packing element between the first surface and second surface; and opening a valve above the packer.